Freckles are common, and you probably wouldn’t think twice if you noticed a random new mark on your skin. That’s what happened to Georgia mom Rebecca Hockaday—but then her freckle appeared to spread.

Hockaday tells Today that she didn’t think it was a big deal when she first noticed a spot on her breast. “I thought, OK, a freckle on my chest. I’ve been out in the sun, no big deal,” she recalled. But a few more popped up and a few months later, Hockaday went to see her dermatologist.

“Honestly, I thought they were sun spots. I thought they were going to say 'just your skin aging,'” she said. “Never in a million years did I think, OK, this is going to be cancer.” But a biopsy found that she had inflammatory breast cancer, a rare and aggressive cancer, and it had already spread to her lymph nodes.

According to the National Cancer Institute, just 1 to 5 percent of all breast cancers diagnosed in the United States are inflammatory breast cancers. The cancer moves quickly, often in a matter of weeks or months and, compared with other types of breast cancer, inflammatory breast cancer tends to be diagnosed at younger ages.

Hockaday, who was 35 at the time of diagnosis and is now 40, went through an aggressive treatment: She had 16 weeks of chemotherapy, had surgery to remove both of her breasts, and underwent radiation treatments twice a day, five days a week. Hockaday was declared cancer-free in September 2013 after 10 months of treatment, but still experienced several health issues from infections related to her breast reconstruction surgery. She’s also not done with chemo: Inflammatory breast cancer has a high rate of recurrence, so Hockaday takes oral chemotherapy and receives monthly injections.

She says she’s sharing her story in hopes it can help other women. "You just do not think that something (that looks) so innocent can turn out this way. I had no pain, I had no symptoms,” she said. “If I can keep anybody else from going through what I went through, it would mean the world to me. I hope that myself or anybody else who has gone through this can educate and raise awareness because moms tend to put ourselves last and we really need to put ourselves first."

It’s scary to think that breast cancer can show up as what appears to be a series of freckles, and the good news is that this is rare.

With that said, it's hard to overstate how uncommon this is as a sign of inflammatory breast cancer. Dennis Holmes, M.D., breast cancer surgeon and researcher and interim director of the Margie Petersen Breast Center at John Wayne Cancer Institute at Providence Saint John’s Health Center in Santa Monica, California, tells SELF that it's "almost unheard of" for inflammatory breast cancer to show up as freckles. "It's quite unusual," he says. "If you have freckles that show up, your first thought or first 50 thoughts shouldn't be 'This is inflammatory breast cancer.'"

This symptom is so rare that some doctors have never heard of inflammatory breast cancer showing up this way. Wendy Woodward, M.D., Ph.D., associate professor of radiation oncology at MD Anderson Cancer Center, tells SELF that this is the first time she’s heard someone describe their initial symptom as a freckle. Instead, she says her patients are more likely to say they noticed what looks like bug bites or spots that look more unusual than freckles on their breasts.

The skin changes show up because inflammatory breast cancer clogs the lymphatic vessels that drain fluid from the breast, Dr. Woodward explains. This can cause the breast to turn red, or otherwise impact its skin color and texture. “It's not uncommon for patients to say the first skin symptom they noticed was very small but it typically progresses to involve the majority of the skin of the breast,” she says, adding that diagnosis tends to come after a significant portion of the breast's skin has changed in a short period of time.

Like many illnesses, some aspects of inflammatory breast cancer can show up differently from person to person.

According to the American Cancer Society, symptoms can include thickening of the skin of the breast, redness involving more than a third of the breast, a harder-feeling breast, an orange peel texture on the skin’s surface, an inverted nipple, swelling, a hot and heavy feel to the breast, tenderness, pain, and itchiness. “The most common presentation is the bumpiness and thickening of the breast itself,” Dr. Reitherman says. “The freckle presentation is extremely rare.”

Inflammatory breast cancer may also move more slowly in some women than in others. “Not everyone has the same experience,” Dr. Woodward says. “Some patients will develop a swollen red breast almost overnight.”

Raquel Reinbolt, M.D., a breast medical oncologist at The Ohio State University Comprehensive Cancer Center–Arthur G. James Cancer Hospital and Richard J. Solove Research Institute, tells SELF that someone with inflammatory breast cancer wouldn't typically have a skin change and no other symptoms. "As the disease progresses, we would typically expect to see more redness, swelling, thickening, and/or warmth," she says.

Overall, experts want you to know that inflammatory breast cancer is rare, and the freckle symptom is especially rare. But, if you suddenly notice something new on your skin and it’s rapidly changing, Dr. Reinbolt recommends making an appointment with your doctor to get it checked out, just to be safe. However, she says, there are a slew of other things this could be, like an infection that can get taken care of with treatment. Dr. Woodward agrees. “Most of these things will not be breast cancer, but knowing that it can be helps to ensure the diagnosis is not missed,” she says.